Research scientist Dr Mark Howden says food security and water shortages in the Pacific should be seen as 'linked' issues requiring serious attention.

Oxfam: Rodney Dekker

One of Australia's leading experts on climate change says Pacific nations are facing serious challenges when it comes to food security.

Mark Howden, from Australia's national science agency the CSIRO, says climate change, rising sea levels and the cost of shipping food to outer islands, are all factors to be considered over the next few decades.

Dr Howden is leading the food security chapter of a forthcoming United Nations report on climate change.

He says population growth in the Pacific islands has stressed the capacity of local food production, which in turn has led to most countries importing their food.

Dr Howden has told Radio Australia's Pacific Beat the capacity to buy and deliver the food will become an issue as fossil fuel prices rise.

"In the longer term, [fuel prices] will increase, and that will increase the cost of food transport to Pacific Islands," he said.

"They are very isolated and those costs can be quite high. So I think, in the future, some of these issues that we're currently seeing will increase simply because of those almost inevitable economic changes."

The chief research scientist says there are also other challenges for the Pacific.

"And then we throw in climate change, which will become in a sense quite wetter and hotter in the equatorial regions, and hotter and drier in most of the rest of the Pacific. And those themselves will have impacts on those islands.

"Sea level rise and salination of fresh water supplies and acidification of some of those ocean waters around the Pacific islands, particularly the more southerly ones, are going to impact on the food web in the ocean as well."

Dr Howden says attention must be focused on tackling food security and water shortage as "connected" issues.

This week, thousands of people in Samoa have had their water supplies rationed as the country's catchments dry up.

"Where water is being used for agricultural production or food processing, clearly then your capacity to actually provide adequate water of adequate quality is going to impact on those food production and processing activities," Dr Howden said.

"We know in a whole range of Pacific Islands that that's either happening or likely to happen, that water's going to become more limited.

"And so as a function of that we'd say that yes, those two are linked."

Meanwhile, a report by the United Nations weather agency, the World Meteorological Organisation, says climate change is taking place and will continue.

The head of the WMO, Michel Jarraud, said the shrinking of ice floating on the Arctic Ocean to a record low in September, and other extremes, are evidence of the impact of climate change.

"Climate change is taking place before our eyes," he said.

The report was produced for the latest round of climate talks in Doha.